The present invention relates, in general, to a bearing assembly for a threaded drive, such as a rolling type screw drive in fine mechanics, and, more particularly, to a bearing assembly of a type having two rolling bearings arranged in side-by-side disposition and received by a restraining element about their outer surface area, with the restraining element being secured by a flange to a housing.
A bearing assembly of this type is illustrated on page 1 under the number 159 063 in publication ZAE, issued by INA Waelzlager Schaeffler KG, and entitled "Lager fur Gewindetriebe" (Bearings for Threaded Drives), September 1996. The bearing assembly includes two axial angular contact ball bearings disposed in O-relationship and received by a massive restraining element which is secured to a housing via a circumferential flange with throughbores for passage of screw fasteners. The restraining element has a radially inwardly directed projection for protecting the bearing assembly at one end (the left hand side) via a fluid sealing. At the other side (right hand side), the bearing assembly is protected by a second fluid seal, formed through threaded engagement of a cover into the restraining element. The securement of this bearing assembly on a shaft is implemented by a precision nut which is provided with an inner thread and screwed on the shaft journal on the right hand side behind the axial angular contact bearings. When the precision nut is tightened, both inner rings of the bearing are moved toward one another, to thereby impart a desired prestress.
This conventional bearing assembly suffers many shortcomings. The restraining element has a complex configuration and can be manufactured only by a complicated, material-removing shaping process. Moreover, the sealing of the bearing assembly is very complicated because the bearing cover on the right side must be manufactured as an additional separate component with an outer thread. Also disadvantageous is the axial securement of the bearing assembly on the shaft by means of a precision nut, because the precision nut not only represents also a separate component and its manufacture is complicated but the provision of such a precision nut requires the formation of a threaded section on the shaft and also requires more space in axial direction for the bearing assembly. Finally, the fact that it is up to the expertise of the customer to adjust the desired prestress of the bearing assembly through tightening of the precision nut is also disadvantageous and may cause problems.